Summary Two helicopters departed from Niagara Falls, Ontario, on a flight to the Bell Helicopter Textron factory at Mirabel, Quebec. At the start of the trip, the aircraft flew in formation in visual meteorological conditions. Helicopter C-FLYO, with the pilot and one passenger on board, followed the aircraft flown by the formation leader. En route, the weather deteriorated; the distance between the helicopters was reduced to 200 feet and the flight continued at low altitude and at a reduced speed. While in hovering flight above an electrical transmission line running across a highway, the C-FLYO pilot made a sudden manoeuvre to avoid a wire, then attempted to land. The helicopter touched down sideways and rolled over onto its right side. The pilot sustained minor injuries; the passenger was uninjured. Ce rapport est galement disponible en franais. Other Factual Information By arrangement between the pilots, the two skid-equipped Bell 206L-3 helicopters departed Niagara Falls in formation flight. The formation leader, flying the lead helicopter, was in charge of radio communications and navigation. The helicopters stopped at Toronto, Ontario, where one passenger boarded each aircraft, and again at Kingston, Ontario, in order to refuel. The two helicopters took off from Kingston around 1321 eastern standard time for a flight to Bell Helicopter Textron in Mirabel. The C-FLYO pilot was certified and qualified for the flight in accordance with existing regulations. He had been flying for the company for eight years. Previously, he had flown helicopters for the Philippine armed forces, where he gained his experience in formation flying. The pilot was responsible for the safety of the aircraft and the passengers on board. Accordingly, he had ultimate authority with respect to the operation of the aircraft during the flight. He reported to the chief pilot. The formation leader was the company owner, who was also chief of operations and chief pilot. The chief of operations is responsible for ensuring that flights are conducted safely, in accordance with government laws and regulations, and in accordance with the standards, practices, procedures, and specifications prescribed in the company operations manual. The two pilots obtained the meteorological information available on actual and forecast conditions along the route prior to the flight. The aerodrome forecast for the Mirabel and Dorval airports indicated a partially obscured sky condition with a ceiling of 300 feet above ground level (agl) and visibility of one mile in rain and haze. At the time of the accident, Mirabel reported a partially obscured sky condition with a ceiling of 300 feet agl, and visibility of one and one-half miles in light rain, light drizzle, and haze. Along the way from Kingston to Mirabel, the meteorological conditions deteriorated. The flight continued at low altitude to about two thirds of the way where, with poor visibility in rain, the C-FLYO pilot landed in a field after losing sight of the formation leader. About 25 minutes later, the pilot of the lead helicopter located the second helicopter and landed beside it. The pilots discussed flight procedures for the remainder of the journey and agreed on the route to be followed to destination. They followed a railway, then a highway, in a northwesterly direction at altitudes between 700 and 100 feet agl. A short time later, the helicopters, at 100 feet agl, crossed a lake 20 miles southwest of Bell Helicopter Textron. The radars stopped receiving the altitude of the lead helicopter when the formation leader switched off his transponder. The aircraft followed a highway to a point about two kilometres east of Saint-Eustache, Quebec, where three electrical transmission lines intersected the flight path. The first two lines were close together at a height of 120 feet; the third line, at a height of 270 feet, was 100 metres further east and was obscured by low cloud. To continue the flight, the formation leader flew over the towers of the first two lines, then hovered to the left and descended before flying under the cables of the third line. Wanting to maintain separation between the two helicopters, the C-FLYO pilot hovered above the first set of cables and watched as the lead helicopter manoeuvred between the power lines about 50 metres ahead of him. At that time, the passenger noticed that the aircraft was moving left and losing altitude. He promptly told the pilot that they were in danger of colliding with the wires. The pilot immediately backed up the helicopter, entered a right-hand turn, and descended for a landing. The aircraft touched down while it was moving sideways to the right. The helicopter bounced twice on the right skid, the main rotor blades sliced through a metal road sign, and the aircraft rolled over on its right side at the edge of the highway congested with rush-hour traffic. The accident occurred in uncontrolled airspace between the Mirabel and Dorval control zones. A helicopter can fly in uncontrolled airspace when the visibility exceeds one-half mile, provided that it flies at a sufficiently reduced speed to allow the pilot to see obstacles in time to avoid them. When the weather is adverse and the pilot must fly at low altitude, he is required to comply with the Air Regulations. Section 534 provides that no person shall fly an aircraft over any open air assembly of persons at an altitude less than 1,000 feet above the highest obstacle within a radius of 2,000 feet from the aircraft or elsewhere than over the built-up area of any city, town, or other settlement or over any open air assembly of persons at an altitude of less than 500 feet above the highest obstacle within a radius of 500 feet from the aircraft.